I don't think that one was ever released as a ROM file. But depending on how the game was programmed, it either can reuse an existing mapper type, or it would require a new mapper type to support it. It's usually not very hard, but it's necessary to exactly know how the real hardware (the cartridge) has been set up.

I dumped my own cartridge to use on my PC and my Pi, and when i try to change and save any option on setup (use the sram of the cart to save the changes) it freezes but the whole game works perfect with its default settings, i have another games from koei with sram (but batteries are almost dead) and those games seems to check if the sram is ok, if not drops an error but game still works prefectly, also i had the exact same problem with other games that uses similar systems (monster hunter in its physical version hangs at selecting language screen)

In an emulator, you need to select the appropriate mapper with SRAM or FlashRAM support. The problem with new cartridges that are not yet officially available in digital form (not even if you want to pay a reasonable price for that) is generally that they use a slightly different form of SRAM or FlashRAM, and of course the corresponding mapper with this SRAM or FlashRAM is not yet supported in the emulators.

DrWho: I don't think they will be lost. If the binary dump has been made, the "hard" work has already been done. Most likely the authors of these games still have the binaries somewhere (and even source code!), and might choose to release a version later on at some point, if the physical copies have all been sold and they choose to do so.

Adding support for the SRAM or Flash is quite trivial. What is needed is the address and mapper type (the support is already there, but the mapper type and address needs to be told to the emulator). The problem is that these are often unknown to the public, but for these new games, the authors are mostly alive and active and might disclose that information, again, if they choose to do so :-).

Failing that because the authors were to disappear, it would probably be quite trivial to look at the running game in the emulator or even the actual ROM binary game machine code to see which addresses it tries to use. Whis will involve some manual labour, but should not be too difficult.

TL;DR: No, these games will not disappear even if their mappers (for non-volatile memory) are not supported in emulators.